The secret cells in the basement of the KGB's Estonian "Grey House" have been preserved as a grim Cold War museum.

This ancient burial mound is accessed by an impressive Greek-built archway.

The oldest church in the Estonian capital is home to over 100 fantastical cemetery coats-of-arms.

"There's nothing there," and other lies the KGB told us.

This historic covered bridge contains a series of macabre paintings that communicate one thing: everyone dies.

In this tiny Iranian town playing on the roof isn't just encouraged, it's the only place to go.

Only a handful of these gorgeous historic waterwheels remain but even those are in danger from local unrest.

A small museum in this border city displays the contraband art that has been stolen back from smugglers.

This gold-winged spire celebrates the first true flight around the world.

The largest bell in the world has been swinging high above a Cologne cathedral for almost a century.

Deadly scalding and one of the largest hot springs in the world.

Mirrors and glass shards cover every inch of this arrestingly beautiful mosque.

This electric green sulphur lake in New Zealand looks like a cartoonish radioactive dump site.

Sitting in the basement of a castle, the largest wine barrel in the world is bigger than most apartments.

Padlocks cover this rickety footbridge with love.

17th century mosque for Shah Abbas' harem.

The largest coin pyramid in the world is a carefully balanced stack of over 1,000,000 pieces.

Ever-growing collection of devils in art.

A black cat protests the City Guild in Riga's Old Town.

Thanks to its heroic service during WWII this Soviet castle has been turned into a monument towered over by a brutalist titan.

A self-funded cemetery with a long list of inhabitants.

This ancient burial site is believed to be one of the first earthquake-protected structures in the world.

The highest paved road in North America winds its way up Mount Blue Sky in Colorado to an altitude of 14,130 feet above sea level.

This man-made mound monument was built out of soil from all across the Polish empire.